Circuit interrupter



Feb. 20, 1951 B. P. BAKER ET AL CIRCUIT INTERRUPTER 3 Sheets-Sheet 1 Filed NOV. 25, 1945 WITNESSES: I I ACQZWV, fZfl/f. M

Feb. 20, 1951 BAKER ET AL 2,542,790

CIRCUIT INTERRUPTER Filed Nov. 23, 1945 1 3 Sheets-Sheet 2 FzyZ Feb. 20, 1951 Filed Nov. 23, 1945 BAKER ET AL 2,542,790

CIRCUIT INTERRUPTER 3 Sheets-Sheet 3 flz'r Opera fed (/0 s [21y flee/ 142153772 WITNESSES:

INVENTORS 3923/0277 ('27 Pfia k2)" and Patented Feb. 20, 1.951

UNITED STATES PATENT OFFICE omourr INTERRU'PTER 'Benjamin F. flaken 'lurtle 1reek,.Pa.,,a;nd Qswald von Mehren, Lorain, Ohio, :assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application November 123,, .1945,-=Seri'al No. 630,350

lt-Claims. 1

This invention relates to circuit interrupters in general and more particularly-tooperating mechanisms therefor. More specifically, our invention relates to an improved operating mechanism for a compressed gas circuit "interrupter of the pressurized chamber type.

Certain aspects of the invention apply in particular to a circuit interrupter of the gas blast type utilizing a pressurized chamber into which extends a pair of terminal bushings of the type ordinarily'used in oil breakers. gas contained within the pressurized chamber is partly used to obtain high dielectric strength within the region enclosed by the chamber, and is also partly used. to effect the extinction of the are drawn in the pressurized chamber by utilizing a suitable arc extinguishing device in conjunction with the gas blast. Preferably, the gas blast; uti lized to effect are extinction, passes out of the pressurized chamber through the terminal bushing itself,

In U. S. patent application, Serial No. 565,456, filed November 28, 1944, now Patent No.'2,5.07,2:I0, issued May 9, 1950,--entitled CircuitInterrupters by Leon R. Ludwig and Benjamin P. Baker and. assigned to the assignee of the instant applica tion a number of features of the invention are disclosed and claimed.

It is an object .of our invention .to provide an improved operating mechanism for a circuit .interrupter of the foregoing type.

The provision of a suitable operating mechanism adaptable for use in a .circuit interrupter of the type'disciosedjin the foregoing implication is rendered difficult in attainment inasmuch as the pole unit mechanism. must lice-capable of providing a long travel inside of the pressure enclosure or tank and preferably a short motion of the member transmitting the motion from the outside to the inside without leakageof the pressure gas, and with means for registering ac.- curately the final closed position for electrical control purposes.

Another object of our invention is to provide an improved operating mechanism for actuating contact means including an operating rod having secured thereto a piston movable in -an.operating cylinder. Preferably, we employ holding means for holding the operating rod in .the closed circuit positionand releasing means .tmeffectfelease of the holding means. Bytheeonstruction which we employ the releasing means has-a relatively short travel as compared to the relatively long travel of-the operating-rod. I

Another object is to provide an improved .operating mechanismof the type desoribed in the preceding paragraph .in which second holding 2 means are employed to 'efiect holding of the releasing means. Preferably, tripping of the second holding means automatically by an interlockingficonstruction, prevents closing operation of the interrupter.

Another object is to provide an improved operating'mechanism suitable tor use in a circuit interrupter inwh-ich interlocking means are providedibetween the-opening and closing'mechanism so that opening takes precedence over the closing operation. Preferably, We accomplish such a result by utilizing an exhaust valve .associated with the closing valve mechanism which is operated -:by the electric means used to trip the breaker.

Another object is .to provide an improved operating' mechanism ,for a circuit interrupter in which the operating mechanism is suppliedwith gas from a pressureeoharnber about the interrupter.

Another object isto provide an improved circuit interrupter inwhich only .one air inlet to the-entire interrupter is required.

Another object 'is'to'provide an improved high speed mechanism for a circuit interrupter in which h'igh speed opening is obtained because of urrla'tching at the top of the lift ro'd'and in which the moving parts have areladzive'le small mass.

Fll1 thr0bCtS relateto :details of construction which will be more apparent hereinafter upon reading the specification taken in conj unction with thedra'wings, in which:

Figure 1 shows a side elevational view partly insectionof a-gas blast type or oircuitinterrupter of the pressurized tank construction embodying our inventionand shown in the closed-'cirouitpositi-on';

*Fig. 2 is an enlarged vertical sectional view through a portion oftheoperating mechanismfor thebreaker shown in Fig. 1;

Fig. 3 is a sectionalview taken along the line 1 11 111 0; Fig. ;2

Fig. 4" is a sectional view taken along the line IV- IV of and ,Fig. 5 is a diagrammatic view of the electrical control circuit for the interrupter.

Referring to the drawings, and more particularly to Fig. 1 thereof. the reference numeral 1 designates'an enclosure of spheriealshape formingapressurized chamber. .Securedas .by welding'to'the lower end. of the pressurized chamber is-a .pluralityoi, in this instance .four, base supports 2. Extending .from the upperend of the enclosure .1 are -ho1l ow ;terminal bushings 3,, A through which extend respe ively .exhaustpassages .3a, 4a and which support, respectivel at 3 their upper ends line terminals 5, 6. A high pressure gas inlet conduit a leads into tank I from a suitable source, not shown, of high pressure gas.

Secured to the lower ends of the terminal bushings 3, 4 are two serially related arc extinguishing units generally designated by the reference numeral I. These units I and other parts of the device disclosed herein have a construction more specifically set forth and claimed in U. S. patent application, Serial No. 624,284, filed October 24, 1945, by Benjamin P. Baker and Oswald von Mehren and assigned to the assignee of the instant application.

Electrically interconnecting the two are extinguishing units I in the closed-circuit position as shown in Fig. 1, is a conducting cross-bar or bridging member 8 which in the fully open-circuit position of the interrupter assumes a position indicated by the dotted lines 9.

The conducting cross-bar 8 is reciprocally operated in a vertical direction by an insulating operating rod I8 which is preferably guided within a bushing I I, the latter being secured by brackets I2 and bolts I3 to the upper wall M of the enclosure I. Positioned on top of the enclosure I is the operating mechanism for the interrupter generally designated by the reference numeral I5 and contained within a metallic housing I6.

An operating cylinder II has its lower end welded as at I8 to the wall I4 of the container I. High pressure gas which is present within the region I9 in the interior of the container I communicates with the space 20 (Fig. 2) below the piston 2| by means of the operating cylinder II. Consequently, high pressure gas within the tank I tends to force the piston 2| secured to the upper end of the lift rod ID in an upward direction, as viewed in Fig. 1. This use of compressed gas taken from the arc extinguisher enclosure is a distinct advantage in breaker construction since no additional air pipes are required to supply air to the operating mechanism.

The piston 2|, coupled to the operating rod I0, and movable within the operating cylinder II constitutes a fluid motor generally designated by the reference numeral 22.

The piston 2| has an upstanding rod portion 24 having at its upper end integrally formed therewith a latching head 25, the latter being latched or held in the closed circuit position as shown in Fig. 2 by means of two latch pins 26. The two latch pins 26 and the latch head 25 secured to the upper end of the operating rod l0 collectively form a first releasable or holding means generally designated by the reference numeral 21. Each latch pin 28 has pivotally mounted thereon two links 28, as shown more clearly in Fig. 4 of the drawings. The four links 28 have two pins 38 cooperating therewith at their upper ends, the two pins 30 passing through a member 3|. Threadedly secured to the mem her 3! is a rod 32 externally of which is positioned a Sylphon bellows 34. The Sylphon bellows is secured as by soldering at its upper end to a ring 35, the latter being secured as by screws 36 to a cylindrical member 31 having a flange portion 38. The flange portion 38 is preferably secured as by bolts 40 and nuts 4| to a flange 42. The flange 42 is welded as at 43 to the upper end of a metallic cylinder 44.

A metallic insert |2I is provided being threadedly secured at I22 into the lower end of the cylinder 31. The insert I2| has cam surfaces |23 formed thereon to extend the pins 26 laterally to effect release of the latch head 25 during the 4 opening operation. Bumper stops I24 are preferably provided to take the shock during the closing operation.

Welded at 45 adjacent the lower end of the cylinder 44 is a ring-shaped casting member 46. Welded to the lower end of the casting member 48 as at 41 is the operating cylinder II.

Biasing means are employed to bias the piston 2| and operating rod I0 to the open-circuit position, in this instance consisting of a compression spring 49 disposed in the interior of the cylinder 44, having its lower end resting upon the piston 2| and having its upper end in abutting engagement with the flange 38. The rod 32 has its upper end 58 threaded and cooperates with nuts 5| and 52 to rigidly secure in place a spring plate casting member 53 which is biased downwardly by a battery of compression springs, in this instance comprising the two coacting compression springs 54, 55. The springs 54, 55 are positioned within a housing 55 having at its lower end a flange portion 51 which is maintained in position by the bolts 48 and nuts 4|.

Integrally formed with the housing 56 are two upstanding support plates 58 more clearly shown in Fig. 3, and only one of which is shown in Fig. 2. A pin 59 extends through the upper ends of the support plates 58 and pivotally mounts a second releasable or holding means generally designated by the reference numeral 60 and in this instance includin a latched plate BI. The latch plate 8| is pivotally mounted on the pin 58 and has a notched portion 62 provided adjacent its lower end which serves to latch a hold in the closed-circuit position as shown in Fig. 2 a roller 63 pivotally mounted on a pin 64, the latter in turn extending through two legs 65 preferably integrally formed with the casting plate 53.

A latch trigger 66 is pivotally supported on a pin 61, the latter extending through both support plates 58. A tripping electromagnet generally designated by the reference numeral 68 is provided consisting of a solenoid 69 which serves to actuate when ener ized an armature I0, causing the latter to move a push rod II upwardly into engagement with an adjustable stop I2 secured to the right-hand end of the latch trigger 68.

A compression spring I3 is provided to bias the latch trigger I56 in a clockwise direction, as viewed in Fig. 2, about the pin 81. The lower end of the compression spring I3 abuts against a portion I4 integrally formed with the housing 56.

An auxiliary switch generally designated by the reference numeral I8 is employed to actuate control contacts and to indicate the open and closed positions of the mechanism. Preferably, the auxiliary switch I8 is actuated by a bell crank I9 pivotally mounted on a pin and having two leaf springs 8|, 82 secured thereto. Positioned between the leaf springs 8|, 82 is a pin 83 secured to the left-hand end of an indicating lever 84, the latter being pivotally mounted adjacent its right-hand end on a pin 85 extending through one of the support plates 58.

A closing electromagnet generally designated by the reference numeral 89 is provided to effect a closing operation of the interrupter. The closing electromagnet 88 when energized actuates a pilot valve 90. The pilot valve 90 controls the flow of high pressure gas from the tank I through a high pressure conduit 9| by valve means generally designated by the reference numeral 92. The valve means comprises a valve member 83 aciegveo which is of the double actingtype andccmiirolsv cured to the valve-stem 96"is a pistonSI biased upwardly by a compression spring 98. Thusythe compression spring 98 serves to 'bias the valve means 92 to the position shown'in Fig; 2. A nut 99 threadedly secured-to the upper end of the valve stem 96. serves to h'ol'd the ipiston'9l'rigidly in placeto thevalve' stem 96.

:The valve stem '96 has its upper end bored to guidably' receive a stem 102, the *upper end of which'is securedto a dumpvalve I03 controlling an exhaust" port I'I. Theiupperendofthe dumpvalve I03 is extended to be rigidly connected to a rod I04, the upper end of which is pivotally connected by means of a pin I05 to therighthand end of a lever I06. The lever If06 pivotally rotates about a fixed pivot consisting of a pin I07, the latter passing through-only'one of the support plates 58. An aperture 'I08 is provided in theiatched trigger 66 toaccOmmOdatethe rod I04. Apin III passes through the 'rod I0'4'and is engaged by two bosses I-I2 integrally formed with the latched trigger 66. Thus, when the tripping electromagnet '68 is energized to cause counterclockwise rotative movement of the latchedtrigger 06, andas soon as it has rotated far enough to unlatch member 6*I, the bosses IIZ engage the pin I-II passing through the rod I04 to maintain thedump valve I03 open. The'purpose for this arrangement will be more clearly understood by the description given hereinafter.

Provided 'in the casting member 46- is-a passage-I I5 controlled by the pilot valve 90andcommunicating when the pilot valve 90' is 'open by means of the passage I I8 to thespace' I'I'I above the piston 91. The space I I8 below the pistonfll" is in communication with the atmosphere byway of the exhaust ports H9, a plurality ofwhich are provided. A bleeder opening I25 is provided to permit exhausting of air from the space I'I'T above the pistonS'I.

It will be observed that the rod. 32, casting v member 53, springs 54, 55'and cam surfaces I23 collectively form a releasing means generally designated by the reference numeral I26 for the first releasable orholding means 21'.

Referring more particularly to Fig. 5' which shows the electrical control circuit forthe interrupter, it will be observed that we have provided a protective relay I3I having a winding energized by the current flowing'through a winding I32 which is. responsive to'fthe flow ofcurrent passing through the power line 133 controlled by the interrupter. The control. circuit is preferably energized by a source of power which consists of a ne ativev line I34 and a positive line I35 as indicated in Fig. 5. "Back contacts I38 of the auxiliary switch 1.8 control the electrical circuit througha-greenlight I55 which is lighted when the "breaker is in the open position, as shown in Fig. 5. Front contacts I31 of the auxiliary switch 18 control the circuit througha red light I54 which is'lightedwhenthe breaker is in the closed position, not shown in Fig. 5. The front contacts I38. of the protective relays I3I are in shunt with a trip button I39.

We provide an interlock relay I40 which deenergizes the closing circuit when the opening circuit is energized. The Winding for 'the'interlockrelay I40 extends through front contacts I4I of the auxiliary switch 181.. The .interlockrelay I40 has a pair of front contacts I42 which serve to maintaina'shunting;circuit about both the trip button I39 andthe front contacts 1380f thepr0- tective relay I3I.

Thus, momentary pressing of the trip, button 'I39or momentar operation of the protective relay I3 I will serve to'energize the interlock relay I40, closing the "front contacts I42 and maintaining a circuit around the trip button [39 or contacts I38 to insure completion of the openingoperation. The interlock relay I40 is provided with-a pair'of-back contacts, I43'which are. in series circuit'with the winding through the el'ectromagnet 89.

A closing relay I44 is provided which is energized during "the closing operation. The closing relay I44 has a pair of front contacts I45 which arein. series with th'e'windln'g through 'theelectromagnet 89. The closing relay I44 also has-anotherpai'r of front contacts [4H3 whichprovi'de a shunting circuit about the closing button I53. An anti-pump relay I49 is provided having a pair of back contacts I50 which are in series with the winding through'the closing relay I64. The-antipump relay I49 also has a pair of 'front contacts I5I which serve to maintain the winding of the anti-pump relay energized following opening of the front contacts. I52 of the auxiliar switch 78 during the opening operation to prevent pumping. This electrical control feature is well known in the art, and a further description thereof appears unnecessary.

The operation of the interrupter will now be explained; In the closed circuit position, as shown in Figs. 1 through 4, the electrical -circuit therethrough extends from the linetermina'l 5through the terminal bushing3, left-hand arc extinguishing unit I, cross-bar B,,.right-hand are extinguishing unit 'I to the right-hand terminal bushing '4' to the right-hand line terminal 6. To open the breaker, either the trip button I38. is manually operated, or. the. protective relay [31 is operated by an overload passing'through the line I33 to close the front contacts I38. This energizes the windings of the interlocking relay I40- and the tripping electromagnet 68. Back contacts I43 of the interlock relay -I'40"open to break any circuit through'the electromagnet 89, which provides an electrical interlock feature between the opening'andolosing. circuits, thus giving preference to the opening. circuit. Also, front contacts I42 of the. interlock relay I40 closes to maintain a circuit around the trip button I39 or the front contacts I38 of the protective relay I31, as previousl mentioned. This insures completionof the opening operation.

The energizing of the tripping electromagnet 68 effects upward movement of the armature"!!! and hence push rod II. This causes counter clockwise rotative releasing motion of the latch trigger 66 to release the latch plate 3!, and su f ficient' overtrave'l to permit the bosses M2 to strike the pin I II to thereby maintain the dump valve I03 open as long as electromagnet 58"is energized.

The latch plate 6I when permitted to move counterclockwise releases the roller '53 to thereby permit the compression springs 54", 55, 40 and the acceleratingsprings associated with. the units 1 to force the releasing means I26 and the operating rod I10. downwardly a distance L as indicated in Fig. 2. The pin 54 passing through the indicating lever .84 actuates the auxiliary switch I8 by clockwise rotation of the bell crank'l'S. Also, the downward movement of the releasing means I20 causes thedatc'h pins ZGtospread outwardly by virtue ofthe cam surfaces I23 'to effeet release of the latch head 25. Since the valve means 92 is in the position shown in Fig. 2, high pressure gas exists on both sides of the piston 2! and hence the net downward force exerted by the compression spring 49 will force the piston 2! to move downwardly rapidly a considerable distance within the operating cylinder I? to efiect separation of the contact means disposed within the arc extinguishing units I.

It will be observed that although the operating rod I and piston 2! have a considerable length of travel, the releasing means I26 only has the relatively short travel measured by the distance L. The Sylphon bellows 34 is employed to prevent high pressure gas which is adjacent the first latching means 2'! during the opening operation from escaping to the low pressure region 23 adjacent the casting plate 53. The Sylphon bellows construction is possible because of the limited downward opening travel of the releasing means I26. The piston 2| moves downwardly free of the first latching or holding means 21, having no engagement therewith until the crossbar 8 assumes the position 9, as shown in Fig. 1. Thus when the breaker is open, front contacts M! of auxiliary switch '58 open to break the energizing circuit through the tripping electromagnet 68. The interrupter is now fully open, all of the circuits being deenergized except the circuit passing through the green light i555.

To close the interrupter, the closing button I 53 is pressed, even though momentarily. This energizes the winding of the closing relay 544. The front contacts I45 of the closing relay I44 close and hence energize electromagnet 89. Also, the

front contacts I46 of the closing relay E44 close and maintain the circuit through the winding of the closing relay I44 around the closing button I53. Thus, momentary closing or the closing button I53 is sufficient.

The energization of the electromagnet 89 causes opening of the pilot valve 98. This permits high pressure gas passing upwardly from the enclosure I through the high pressure conduit 9! to pass through the passage I I past the pilot valve 90 through the passage II6 to the region iI'I above the piston 91. At this time it will be observed that the dump valve 503 is closed since the tripping electromagnet 68 is deenergized and compression spring 13 restores the trigger latch clockwise until the latching end thereof rests against the end of the latch 6!. This movement is sufficient to permit the bosses I I2 to move away from the pin I I I. Also, it is to be noted that the compression spring 15 tends to maintain the dump valve I03 closed against the exhaust port IOI. Consequently, in view of the above state of affairs, the high pressure gas passing from the conduit 9! into the space II! and at a greater rate than it is exhausted through the bleeder opening I25 will force the piston 9! downwardly against the force exerted by the compression spring 98 to cause the valve member 93 to close the inlet port 94 and open the exhaust port 95.

This exhausts high pressure gas above the piston 2| through the exhaust port 95 and out II9 into the atmospheric region. The high pressure gas within the tank 3 communicating with the region biases the piston 2! upwardly, and since the upper side of the piston 2! communicates with atmosphere through the exhaust ports 95, I I9, the high pressure gas in the region 20 will serve to move rapidly the piston 2! and hence the operating rod I0 upwardly toward the closed circuit position of the interrupter.

the latch plate 6!.

Near the end of the closing stroke the latch head strikes the latch pins 26, the latter being biased toward each other by suitable means not shown, to effect latching or holding engagement of the piston 2! and operating rod I0. The continued upward movement of the piston 2! causes the releasing means I26 to move upwardly the relatively short distance L to force the roller 63 upwardly into the notched portion 62 and hence to effect clockwise rotative latching movement of The compression spring I3 forces the latch trigger 68 into latching engagement with the latch plate 6!, and at the fully closed position of the interrupter, as shown in Fig. 2, the roller 63 strikes the left-hand end 'I'! of the lever I06 to effect opening of the dump valve I03. The parts then assume the position shown in Fig. 2, and the breaker is fully closed.

Closing of the front contacts I52 of the auxiliary switch I8 in the closed position of the breaker energizes the winding of the anti-pump relay I49 which closes. Opening of the back contacts I50 of the anti-pump relay I49 breaks the energizing circuit through the winding of the closing relay I44. The closing relay I44 hence opens, and the front contacts I46 thereof also open to break the energizing circuit through the winding of the anti-pump relay I49. Also, the front contacts I open to break the energizing circuit through the winding of the electromagnet 89. The breaker is now fully closed, all the circuits are deenergized except the electrical circuit passing through the red light I54.

It will be observed that not only is there an electrical interlock circuit provided between the tripping electromagnet 68 and the electromagnet 89 by virtue of the interlock relay I40, but also structurally we provide an interlocking arrangement so as to make the opening operation take precedence over closing operation of the breaker. More specifically, when the tripping electromagnet 68 is energized to cause counterclockwise rotative movement of the latch trigger 66 which effects engagement between the bosses i I2 and the pin II! when it has slightly overtraveled its unlatching position to maintain the dump valve I03 open, should the electromagnet 89 be energized at this time to effect opening of the pilot valve 90, the exhausting of air from the region II! above the piston 9! through the exhaust port I0! and bleeder opening I25 is greater than the passing of high pressure gas from the passage II5, II6 into the region II'I. Consequently, the pressure is maintained sufiiciently low in the space H! so that the compression spring 98 maintains the piston 91 in its raised position, as shown in Fig. 2, to thereby equalize the pressure on the piston 2! and hence to permit accelerating spring 49 to cause opening motion regardless of the state of energization of the electromagnet 89. Thus, we structurally provide an arrangement whereby should both the electromagnet 89 and the tripping electromagnet 68 be energized at the same time, the opening operation would take precedence over the closing operation.

It is to be observed that in the fully closed circuit position of the interrupter, as shown in Fig. 2, the exhaust valve I03 is open. It is forced open since the roller 63 strikes the left-hand end 'I'! of the lever I06 in the closed circuit position. This has the following advantage. Assume that in the open circuit position of the interrupter a fault condition still exists in the line I33. During the closing operation when the electromagnet 89 is energized, high pressure will exist in the space acaaaao HJ above the piston '91. Whenthe. breaker reaches, its fully. closediposition, .it .will betripped open-by operationof theprotective relay. I3].

However, even though the=trippingselectromagnet -68 is.energized, the pistonllwilldnotmove down-- wardly unless the pressure is equalized: thereon, that is, highpressure-gasexists on thetop/of the piston-2l as welllas-onsthebottom thereof. Thus, valve member 93must be insthe position shown in Fig. 2 as soon as possible toiinsure-rapid opening of the piston 21'- and-hence operating-rod I0. By opening the dump-valve I03-at the extreme end of the closingstroke, shouldthe breakerhave been closed on ashortcircuit, theJrapid-dumping of air from thespace. HJ will permit valve member 9 3 .to quickly move to its raised. position, as shown in Fig, 2, .therdump valve I03-cooperating with the bleeder-opening; l-to. rapidly exhaust high pressure gas "from n the space l-al 'l. Thus, by causing the'opening of the dumpwalve l03-at1the extreme endof the closing strohe, we%providean operating mechanismrwhich is especially desirable where rapid opening is desired-when the breakerig-closed:on-ashortcircuit.

From the-foregoing; description, it willbe-iapparent that we :haveaprovided 1 an-improved=operating mechanism fora?circuit interrupter of the gas blast type in whichiarrelatively long travel of the-lift rod is-desired, and where-it isnot desired to have a-relatively long-travel of the-mechanism usedto initiateaopening .movement' of the .lift rod. Thus, with the construction illustrated, although thepiston 2-1 travels-aconsiderable distance,the

releasing means l2 6 1 has only the slight travel: L. A Sylphon bellows constructionwfoesea ing the openinginto theipressurechamber-through which the operatingimechasnism' is controlled is thereforepossible.

It will be furthermore understood'that certain features of the invention 1, are applicable not only to circuit interrupters. of the pressurized tank construction but to any type *Ofr circuit interrupter in whichitxis desired to-have the-operating rod setfree after its initiation, and controlled exclusively thereafterby biasing;means,such*:as an accelerating'compressionspring;

The construction :illustrated not only provides rapid opening and closin'gfoperations'but'ienabl'es the opening operation to: take'iprecedence .struciturally overthe. closing operation; Furthermore, the mechanism ;isadaptableior highaspeed reopening when closing: the interrupter during the existence of short circuit conditions in thefi power line '33;

Although we have:.-=shown:and described aspecific structure, it is to be clearly understood that the same was merely for-the purpose of illustration andthat changesland modifications may readily be made therein by those skilled in the art without departing-iromz-the spirit and scope of the appended claims.

We claima's our-invention.

1. In a circuit interrupter, contactmeans for establishing anar'c, an'operati ng rod" for actuating the contact means, anloperating cylinder, a piston secured to the operatingrod andmovable within the operating cylinder, means for admitting gas pressure to said cylinder. on bothsides of said piston, means holding, the operating rod :in the closed-circuit position, means biasingthe operating .rod' to the open-circuit"position, and means for equalizing the pressure on both sides of thepiston during the opening operation.

2. In a circuit inter.rupter,,means defining, a pressurized chamber, contactmeans for estabvlishinganrarc within thepressurized chamber, an

operating rodfor actuating the contact means, anoperating cylinder,-a pistonsecured to the operating rodancl movable within the operating cylinder and one side of said piston being subjected to the pressure insaid chamber at all times, means holding. the operating rod in the closed circuitpositionmeans biasing the operating rod .to the open circuit position, and means for admitting pressure to the other side of the pistonto permitopening operation.

3. Ina circuit interrupter, apressurized chamber, a-contact operating rod extending into the chamber and movabletherein, an operating cylinder, a-piston movable withinthe operating cylinder andsecuredto one endof the operating rod,

means biasing the piston in such adirection so as to movethe operating rod into contact opening position, means subjecting bothsides of the piston to high pressure gas from the pressurized chamber during the opening'operation, and means permitting exhausting of high pressure gas on one side of the pistonduring the closing operation to permit the-high pressure gas withinthe pressurized chamber to effect closing motion oi the piston.

4. In a circuit interrupter, contact means for establishing an-arc, operating meansfor thecontact means includinganoperating'rod with-a'relatively long travel first releasable means for holding the operating rod in the closed circuit position disposed in a -regionof high pressure, releasing means for the first releasablemeans having a relatively short travel, and second holding means for holding the releasing means disposed in a regiorrof relatively'low pressure, a Sylphon bellows movable withthe releasing means.

5.'In acircuit interrupter, contactmeans for establishing an arc, an operating rod for actuating the contact means; an operating cylinder having one end communicating with a region of high pressure, a piston securedto the operating rod and movable within the operating cylinder, means'defining a passage for admitting high pressure to the other end of said cylinder means biasing the pistonin the opening "direction, meansequalizing the high pressure on both sides of the piston during the opening operation, first holding means for holding the'operating rod in the closedposition, releasing means for the first holding means, and second holding means for holding the releasing means,

6. In a circuit interrupter, contact means for establishing an arc, an operatingrod having a relatively long travel for actuating-the contact means, an operating cylinder, at piston secured to the. operating rod and movable within the operating cylinder, means for admitting 'gas'pressureto said cylinder on both sides of said piston, means biasing the piston in the opening direction, means equalizing pressure on both sides of the piston during the opening operation, first holding means for holding the operating rodin the closed position, releasing means for the first holding means having a relatively short travel, and secondholdingmeans for holding the releasing means.

'7. In a circuit interrupter, contact means for establishingan arc, an operating rodhaving a relatively long travel for actuating the contact means, anoperating'cylinder, a piston secured-t0 the operating rod and movable within the operating cylinder, means foradmitting gas pressure to Said cylinder on both sides of saidpiston, meansbiasing the pistonin the opening direction,

means equalizing pressure on both sides of the piston during the opening operation, first holding means for holding the operating rod in the closed position, releasing means for the first holding means having a relatively short travel, second holding means for holding the releasing means, means providing relatively high pressure adjacent the first holding means during the opening operation, means providing relatively low pressure adjacent the second holding means, and Sylphon bellows means movable withthe releasing means to prevent intercommunciation between the high pressure and low pressure regions.

8. In a circuit interrupter of the gas blast type, contact means separable to draw an arc, a fluid motor including a pressure actuated piston movable axially for actuating the contact means, first holding means for holding said piston in the closed circuit position, means biasing said piston toward the opening direction, releasing means disposed in axial alignment with said piston and movable axially relative to said piston to release the first holding means, means biasing the releasing means in releasing direction, and a second holding means for releasably holding the releasing means.

9. In a circuit interrupter of the gas blast type, contact means separable to draw an arc, a fluid motor including a pressure actuated axially movable member having a relatively long travel for actuating the contact means, first holding means for releasably holding the member in the closed circuit position, means biasing the member toward the opening direction, releasing means disposed in axial alignment with said member to be moved axially relative to said member and having a relatively short travel to release said first holding means, means biasing the releasing means in releasing direction, and second holding means for releasably holding the releasing means.

10. In a circuit interrupter, contact means for establishing an arc, operating means for the contact means including an operating rod with a relatively long travel, first releasable means for holding the operating rod in the closed circuit position disposed in a region of high pressure, releasing means for the first releasable means having a relatively short travel, and second holding means for holding the releasing means disposed in a region of relatively low pressure, and means preventing communication between the high and low pressure regions.

11. In a circuit interrupter, contact means, an operating rod in two separable parts for causing the actuation of the contact means, an auto matic disconnect means between the two parts to permit separation of said parts and independent movement of one of the two parts upon movement of the operating rod in the opening direction, restraining means normally restraining said automatic disconnect means, and electroresponsive means operable to effect release of said automatic disconnect means.

12. In a circuit interrupter, a pressure chamher, contact means within the pressure chamber, an operating means in two releasable parts for causing the actuation of the contact means, a releasable connection between the two parts within the pressure chamber, and means for effecting the release of the releasable connection to permit independent movement of one of the two parts upon movement of the operating means in the opening direction.

13. In a circuit interrupter, contact means,

an operating means in two separable parts for causing the actuation of the contact means, a releasable connection between the two separable parts, a piston connected to the operating means between the contact means and the releasable connection, and means for effecting the release of the releasable connection to permit separation of said parts and independent movement the part connected to the contact means upon movement of the other part in the opening direction.

14. In a circuit interrupter, a pressure chamber, contact means within the pressure chamber, an operating means in two releasable parts and extending into the pressure chamber for causing the actuation of the contact means, a releasable connection between the two parts within the pressure chamber, means for eifecting the release of the releasable connection to permit independent movement of the part within the pressure chamber upon movement of the part of the operating means outside of the pressure chamber in the opening direction, and a piston within the pressure chamber and secured to the part which moves independently in the opening operation.

15. In a circuit interrupter, contact means, an operating means in two separable parts for causing the actuation of the contact means, a releasable connection between the two parts, means effecting the release of the releasable connection during the initial portion of the opening operation to permit separation of said parts and independent movement of the contact actuating part in the opening direction, holding means for the operating means, and the re-engaging movement of the independently movable part moving the other part during the closing operation to position where it is held by the holding means.

16. A circuit interrupter including separable contact means, operating means for said contact means including anoperating rod having a relatively long axial travel to open and close said contact means, a first holding means for releasably holding said operating rod in closed position, releasing means disposed in axial alignment with said operating rod and having a relatively short axial travel relative to said operating rod to actuate said first holding means to thereby release said operating rod, a second holding means for releasably holding said releasing means and operable to effect release of said releasing means, spring means biasing said releasing means in releasing direction and operable upon operation of said second holding means to actuate said releasing means, and an operating piston disposed between said contact means and said first holding means.

BENJAMIN P. BAKER. OSWALD VON MEHREN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,015,633 Dorfman Sept. 24, 1935 2,153,400 Trencham Apr. 4, 1939 2,281,337 Stegelitz et al. Apr. 28, 1942 2,286,023 Strong June 9, 1942 2,290,320 Duffing July 21, 1942 2,292,096 Thumim et al Aug. 4, 1942 2,360,687 Johnson Oct. 17, 1944 2,408,199 Cumming et a1. Sept. 24, 1946 2,425,168 Wilcox et al Aug. 5, 1947 2,447,656 Ludwig et a1 Aug. 24, 1948 

